Potato Enzyme Lab
Objectives:
 Observe the breakdown of hydrogen peroxide toxin by potato’s enzyme
catalase.
 Determine if temperature and pH affect enzyme effectiveness.
Background Information: Some plants such as potato and spinach have very
high levels of catalase, an enzyme that works on hydrogen peroxide to yield
water and oxygen. Hydrogen peroxide is a toxic chemical that is produced in
many organisms during metabolism. Organisms must get rid of this toxin to
survive. Catalase can be found in most tissues of the body, along with plant
material such as potatoes.
Materials:
Potato (cubes)
Test tubes (2 sets of 3)
Test tube rack
glass stirring rod
Vinegar (10 ml)
Hydrogen Peroxide (60ml)
baking soda
Procedure:
1. Take several pieces of cubed potato and put into test tubes. Label 1 set of test
tubes: heat, room temperature, cold. Keep the “room temperature” test tube in
the test tube rack. Take the “heat” test tube and put into boiling water for 5
minutes. Put “cold” test tube in bowl of ice for at least 5 minutes.
2. Put all three test tubes in test tube rack. Add 10ml of hydrogen peroxide to
room temperature test tube first. Observe the reaction and record. If there is
catalase present foam should be produced. The foam produced is a result of
catalase converting hydrogen peroxide into water and oxygen; the bubbles are
filled with this oxygen. The more bubbles produced the faster catalase is
carrying out this reaction, or the more catalase present.
3. Next, add 10ml of hydrogen peroxide to the “cold” test tube, record
observations. Lastly, add 10ml of hydrogen peroxide to the “heat” test tube.
Record your observations.
4. Put several pieces of cubed potato into the second set of test tubes. Label the
test tubes: acid, neutral and base. Add a pinch of baking soda to the “base” test
tube. Add 10 ml of vinegar to the “acid” test tube. Do not add anything to the
“neutral” test tube. Take the glass-stirring rod and mash the potato cubes. Let
the test tubes sit for 5 minutes. Add 10ml of hydrogen peroxide to each test tube
and record your observations.
Group members:
1. What test tube is the control group? Why?
2. Formulate an If/then hypothesis. Remember if/then hypothesis always
follow the same form of if the ________________(dependent variable) is
related to the _______________(independent variable) in ________ way,
then given _____(condition) I predict ______________(outcome).
DATA AND OBSERVATIONS
Test Tube
Observations
Analysis questions:
1. Did you support or refute your hypothesis? Why? What data leads you to that
conclusion?
2. What did the catalase do? How do you know?
3. What did grinding the potato up do to the rate of reaction? Why did this change the
rate?
4. What did cooking the potato do to the rate of reaction? What conclusion can you draw
Conclusion: Briefly summarize the experiment/restate the objective. Restate your
hypothesis. Was your hypothesis supported or refuted? Why or why not? Include data in
your explanation.